Thiotepa-based conditioning for allogeneic stem cell transplantation in acute lymphoblastic leukemia-A survey from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

In this study, we analyzed a thiotepa-based conditioning regimen for allogeneic stem cell transplantation in adults with acute lymphoblastic leukemia, using the EBMT database. A total of 323 patients were identified. The median age was 43 years. Disease status at transplant was first complete remission (CR1) in 48.9%, CR2 in 21.7%, CR3 in 6.2%, while 23.2% of the patients had an active disease at the time of transplant. This was performed from a HLA-matched sibling (49.8%) or a matched-unrelated donor (51.2%). The incidence of acute graft-vs.-host disease (GvHD) (grade > II) was 26.6%, while chronic GvHD occurred in 35.9% of the patients at 1 year (24.6% with extensive disease). With a median follow-up of 16.8 months, the nonrelapse mortality was 12.4 and 25.3% at 100 days and 1 year, respectively. The relapse incidence at 1 year was 33.3% with no difference for patients in CR1 (27%). The one-year leukemia-free survival (LFS) and overall survival (OS) were 57 and 66%, respectively for the entire cohort and 50 and 66%, respectively in patients in CR1. Thiotepa/busulfan ± melphalan (n = 213) in comparison to thiotepa/other (n = 110) conditioning regimen resulted in higher relapse incidence at 1 year (34.9 vs. 30.3%, P = 0.016) and lower LFS (38.8 vs. 45.9%, P = 0.0203), while nonrelapse mortality (23.8 vs. 26.3%, n.s.) and OS (59.6 vs. 51.1%, P = 0.109) did not differ. This large study suggests that a thiotepa-based conditioning for allogeneic transplantation in acute lymphoblastic leukemia is feasible and effective, with the main outcomes being comparable to those achieved with other regimens. Am. J. Hematol. 92:18-22, 2017.